As displays combined with input means, display devices with touch panels are widely used in electronics, such as laptop computers, OA equipment, medical equipment, car navigation devices, portable electronic devices such as mobile phones, and personal digital assistants (PDAs).
Here, different types of touch panels are known, including capacitive type, optical type, ultrasonic type, electromagnetic induction type, resistance film type, and the like. Among these, in particular, capacitive type, which detects input coordinates by monitoring changes in the electrostatic capacity between a finger tip and a conductive layer, is becoming the mainstream of current touch panels on par with resistance film type.
As a conventional display device with a capacitive touch panel, for example, a device is known to have: a display panel formed by an organic EL display (OLED) panel and a barrier glass layer which is positioned closer to the viewing side than is the OLED panel; an anti-reflective circularly polarizing plate formed by a quarter wavelength plate and a polarizing plate which is positioned closer to the viewing side than is the quarter wavelength plate; a touch sensor unit; and a cover glass layer, which are stacked in the stated order from the light emitting side towards the viewing side (for example, JP2013-41566A (PTL 1)). Additionally, a conventional display device with a capacitive touch panel has a touch sensor unit that is formed with, for example, two transparent base plates, each having a conductive layer formed on a surface thereof, stacked together such that the conductive layer of one transparent base plate face a surface of the other transparent base plate on the side opposite where the conductive layer of the other transparent base plate is formed (for example, JP2013-3952A (PTL 2)).
Such a conventional display device with a capacitive touch panel has a function for preventing incident external light (natural light) being reflected at the surface of the OLED panel (particularly the surface of an electrode in the OLED panel) from making visual recognition of the displayed content difficult.